Depression of carbonaceous material in flotation



Patented Jan. 24, 1939 UNITED STATES PATENT OFFICE DEPRESSION OF 'CARBONAOEOUS MATERIAL IN FLOTATION Robert 'B. Booth, 'Springdale, Conn., assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application February 1, 1938.

Serial No. 188,075

This invention relates to the flotation of car- The amounts of dextrine required will vary to bonaceous precious metal ores. some extent with the ore and with the dextrine. In the past, a number of precious metal ores In all cases, it is necessary to use sufiicient containing carbon have presented a serious probamounts of dextrine to effectively depress carbon lem in ore dressing. The carbon tends to be slimy but the amount Should not be large enough to 5 and also floats readily. The sliminess of the carseriously depress precious metal values. To some bon actually affects the float in many cases and extent this may be considered as a compromise the presence of carbon in the concentrate is a but it is an advantage of the present invention distinct disadvantage when it is desired to subthat an amount of dextrine, particularly of yellow 10 ject the concentrate to cyanidation. It has been corn dextrine, which gives very efiective carbon 10 proposed to depress the carbon during flo'tat'ion depression is well below the amount that seriusing a starch reagent prepared by boiling starch ously depresses precious metal values, particuwith caustic soda. When used with precious larly in pyritic ores. In general, efiective 'demetal ores, however, this soluble starch does not pression of carbon begins with amounts of dexgive good metallurgy because when used in trine from about 0.2 to 0.3 lbs./ton, depending 15 amounts sufficient to give even fair carbon deon the dextrine. In the case of some ores, pression, it tends to depress some of the constitamounts of dextrine as high as 6 lbs/ton have uents carrying the values particularly in the case been used with success. In general, however, it or pyritic gold ores. is desirable to keep the dext'rine as low as pos- In the present invention, I have found that sible and with most ores amounts of dextrine 20 dextrines and particularly yellow corn dextrine from I to 2 lbs/ton of ore give good results but possess all of the advantages of highly eflicient of course the invention is not limited to this parcarbon depression without possessing the dis ticular range. advantage of excessive depression of precious The invention will be described in detail in the 5 metal values when used in amounts sufiicient to following specific examples in conjunction with 5 elven, e t ve Carbon depression. In this manvarious dextrines and with different typical cary using amoun 9f dextline Whi0h give bonaceous precious metal ores. The invention is d carbon p s itbi possible to ta of coursenot limited to the details of the specificf metallurgy Wlth P b Q P examples which are typical illustrations only.

010115 lPetal B h (1 other reagents- V The present invention may be used in rougher 30 f jl Flextrme 1S frequently loosely 5P7; flotation of the ore where desired or it may be plied in the industry to cover a large number used only in a cleanin operation. The advanof degraded cellulosic products. According to tage of the invention is particularly high in the present invention, however, dextrine is used meaning and the efo e best operating p m lts Stnct Sense as covering the pmducts cedure maylinvolve a rougher float without dex- 35 tamed by substantially dry h degradations of trineor with smaller amounts of dextrine cellulosic material such as starch with or without preliminary treatment with material such as I Example 1 acids. The term dextrine will be used in no 40 other sense in the present specification and carbonaceous pyritic gold ore from the Mother 40 a the flotation of precious metal ores and are not claims and is not intended to include materials Lode district was subjected to flotation with and obtained by digesting starch in various aqueous without t use of dextrine. The ore assayed solutions which are sometimes loosely referred to to 0446 om/ton of gold and about 0.59%

dextrmized products' These latter Products carbon The flotation was efiected in Fa er ren do not-exhibit the properties of true dextrmes Vin flotation machines. In both cases the o re was included in the scope of my invention. conditioned t Soda l and "copper Sulfate While all true dextrines show the valuable and the following flotatmn reagents used: seeproperties set out above, different dextrines will qrtdary butyl i tom 1'' fifty-fifty 5o vary in the degree to which they possess these mlxture sodmm methyl" and dlsecondary' properties and in general the best results are obdlthiophosphates ton; and pine tained with yellow corn dextrines Which r t 011, 0.l23-1b-./ton. In one float an additional from the dryheatmg f c starches which 2 lbs/ton of yellow corn dextrine was added to have been pretreated with acids such as nitric the. during the grin in p ra n The acid. a i r metallurgical results are as follows, the first 55 the as against 86%. These important savings are met with a negligible loss in grade.

Feed Concentrate Telling Dist. r Dist. Gold Wt. Wt. Wt. Ratio Gold Wt. Gold oz./ton gs. percent percent conc. oz./ton percent percent oz./ton percent gold gold Example 2 The carbon assays from the flotation products An ore of the same character from the same region was subjected to rougher flotation without dextrine and the rougher concentrate assaying 2.13 to 2.336 ozs./ton of gold and 8.23% carbon cleaned without additional promoters. In both cases the flotation was in Fagergren machines. The metallurgy appears in the following table in which the first line is the cleaning operation without dextrine and the second in the presence of 2 lbs/ton of yellow corn dextrine:

were as follows:

Feed Recleaned Recleaned Cleaner concentrate tailing tailing It wil be noted that in the case of cleaning of concentrates, a very great increase in grade is obtainable with larger amounts of dextrine with It will be noted that a very marked increase in grade is obtained with negligible loss of recovery because the 2.32% lower recovery representsmiddlings which are returned to the rougher circuit and the values of which are for the most part recovered. t

In order to obtain a still further improvement in grade, the original concentrate was subjected to a cleaning and recleaning operation in the presence of additional flotation reagents. The concentrate was first conditioned with 4 lbs/ton of yellow corn dextrine and floated with 2 lbs./ton of copper sulfate, an additional pound of yellow corn dextrine and 0.2 lb./ton of secondary butyl xanthate. This concentrate was then mixed with a further pound per ton of yellow corn dextrine giving a total of'6 lbs/ton and recleaned with the same amounts addedof copper sulfate and secondary butyl xanthate.

A second test was made with the same amounts I of reagents except that instead of stage feeding the dextrine in the cleaner float, all of the 5 lbs./ton'of the dextrine present in this operation were introduced in the conditioning. The results are shown in the following table, the first line being the test with stage feeding and the Feed Concentrate Tailing Dist. D185. Gold Wt. Wt. Percent Ratio Gold Wt. Gold ozs./ton gs. percent wt. conc. ozsJton percent percent oz./ton percent gold gold only a slight loss in recovery, most of which is regained as the recleaner tails pass back into the cleaner circuit.

Example 3 A copper-gold ore containing graphite and having the following assay for copper, gold and carbon: 7

Gold oz./ton 0. 496-0. 627 Copper per cent 0.91 Carbon do 7. 15

was subjected to flotation in Fagergren machines with and without dextrine. In the case of this ore, the effects of various dextrines were tried. The flotation reagents other than dextrine were as follows: secondary butyl xanthate, 0.05 lb./ton; a fifty-fifty mixture of sodium diethyland disecondarybutyl-dithiophosphates. 0.05 lb./ton; added to the grinding operation, the same amounts of reagent added in a conditioning operation and in addition, 0.45 lb./ton of dicresyldithiophosphate added to the float just prior to the flotation together with 0.078 lb./ton ofa synthetic frother consisting of a mixture of higher aliphatic alcohols and a saturated hysecond without: 7 r drocarbon. The first was carried out in the ab- Feed Recleaner concentrate Recleaner tailing Cleaner tailing Wt. Wt. Dist. Dist. Dist. Gold Wt Ratio Gold Wt. Gold Wt. Gold ozs./ton gs. 3 5i. gg conc. oulton 223? percent oz./ton 2 5? percent oz./ton iffi It will be noted that stage feeding of the dextrine results in a much lower cleaner tail,'less than one half the gold, and a much higher re- 1 covery in the recleaner concentrate, about 95% sence of dextrine and an additional eight tests were carried out with various amounts of yellow and white dextrines, the metallurgical .results and amounts of dextrine appearing in the follow- Percent carbon Percent gold rejected 5 66 6 04 3%39M1Q97 2 6 5 7 L4L 11 1 1 Tailings Gold oz./ton

Percent Wt.

a pulp of the precious metal ore to froth flotation in the presence of a dextrine.

Gold

oz./ton

Concentrate Gold Feed

Dist. Ag

ROBERT E. BOOTH.

Wt. percent 4. A method of floating carbonaceous pyritic precious metal ores which comprises subjecting a pulp of the precious metal ore to froth flotation in the presence of yellow corn dextrine.

5. A method of floating carbonaceous precious metal ores which comprises subjecting the ore to froth flotation in a rougher float in the absence of a dextrine and cleaning the rougher concen- 25 trate thus obtained by froth flotation in the presence of a dextrine.

6. A method of floating carbonaceous precious metal ores which comprises subjecting the ore to froth flotation in a rougher float in the absence of a dextrine and cleaning the rougher concentrate thus obtained by froth flotation in the presence of yellow corn dextrine.

7. A method according to claim 1 in which a flotation and the remainder duringv flotation.

8. A method according to claim 2 in which a flotation and the remainder during flotation.

Tailing Ag oz./ton

The metal- Dist. Ag

Depresssnt Type ing table, together with the per cent of carbon rejected in the tailing Example 4 A silver ore containing about 2% carbon and assaying 17.72 to 17.96 ozs./ton was subjected to flotation in Fagergren machines in the presence Concentrate Wt. percent It will be apparent that dextrine does not act purely as a dispersing agent as it gives results which are greatly superior to those obtained with a pure dispersing agent.

What I claim is:

1. A method of floating carbonaceous precious metal ores which comprises subjecting an aqueous pulp of a carbonaceous precious metal ore to froth flotation in the presence of a dextrine.

2. A method of floating carbonaceous precious portion of the dextrine is introduced prior to froth flotation'in the presence of yellow corn portion of the dextrine is introduced prior to dextrine.

3. A method of floating carbonaceous pyritic precious metal ores which comprises subjecting of 0.5 lb./ton of yellow corn dextrine and in a separate test, with 1.5 lbs/ton of a common dispersing agent, namely, water glass. lurgical results Were as follows:

Water glass Yellow com dextrine.

metal ores which comprises subjecting an aqueous pulp of a carbonaceous precious metal ore to CERTIFICATE OF CORRECTIONo Patent No, 2,lLL5,2O6. January 2h, 1959.

ROBERT B. BOOTH.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, lines 29 and 50, in the heading to the table, for "Wta Ag" read Dist. Ag; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Officeo Signed and sealed this lhth day of March, Ac D, 19 9.

Henry Van Arsdale.

(Seal) Acting Commissioner of-Patents. 

